Yuleng Zeng
28 March, 2020
We are going to study fallacies now for two reasons.
The second reason is that understanding why these patterns of argument are fallacious will help us understand the nature of good reasoning. Just as doctors increase their understanding of health by studying diseases, we can gain clarity about good arguments by seeing what is wrong with bad ones.
For example
If robbery was the motive, then the victim’s money wouldhave been taken. The victim’s money was taken. Therefore, robbery was the motive.
I have a dream that one day this nation will rise up and live out the true meaning of its creed: “We hold these truths to be self-evident—that all men are created equal.” . . . I have a dream that one day even the state of Mississippi, a desert state sweltering with the heat of injustice and oppression, will be transformed into an oasis of freedom and justice. I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character. [Quoted from Let the Trumpet Sound, by Stephen B. Oates]
THE RETURN OF THE PRIVATEERS. A long time ago, politicians hired private companies to do government work. They were mercenary ships, called privateers. We know them as pirates. Today, right here in New York State, politicians are trying to hoist the same old idea. This time around, calling it privatization. Let them get away with it, and privateers will be loose again
This fallacy is committed when one tries to get someone to accept a proposition on the basis of a threat.
Credibility is essential for us to accumulate and expand our knowledge.
We noticed at the beginning of Chapter 4 that we rely on information passed on by other people for much of what we know. Most of us lack firsthand knowledge of theevidence for the theory of relativity, the DNA model of genes, the link between smoking and lung cancer; we accept these and other scientific ideas because we accept the authority of experts in the various fields. We know about historical events largely through the records and memoirs left by our predecessors. We learn about current events from reading newspaper accounts by journalists. Courts of law rely on eyewitness testimony and expert witnesses. Indeed, we can extend the legal concept of testimonial evidence to cover all of these cases.
To evaluate such evidence, we must weigh the credibility of the witness. The arguement goes like this: X says p, thereofre p is true. If such an argument is to have any strength, two assumptions must be true.
In other words, X must be someone who not only knows the truth, but who also tells the truth.
This fallacy is committed when using testimonial evidence for a proposition when the conditions for credibility are not satisfied or the use of such evidence is inappropriate.
advertisers often use celebrity endorsements—a basketball star praises his favorite brand of orange juice, a famous actor extols the virtues of a luxury car. If the role of the celebrity is merely to add glamour, there’s no fallacy involved, because there’s no attempt at logical argument. But the advertiser’s point is usually to persuade you that the product is good because someone you respect says so. That’s a fallacy. Skill on the basketball court does not imply a discriminating taste in orange juice, nor does acting ability give one expertise in judging cars.
It often happens that experts disagree. … What should we do when we encounter such disagreements? The first thing to do, of course, is to make sure that we are dealing with a genuine dispute among experts and not simply an effort by some non-expert to challenge well-established principles or theories. If the dispute is a genuine one, then we have to take both sides into account. An argument that appeals only to one group of experts is fallacious.
Vested interests are an obvious example. When people stand to gain money or other personal benefit from making an assertion, it is reasonable to consider whether that benefit is biasing their judgment. Since celebrities are paid to appear in advertisements, for example, they have an obvious motive for praising the product regardless of what they really think about it.
Emotional commitments are another red flag. When a jury is being picked for a trial, potential jurors are typically excused if they have personal connections with anyone involved in the case. For the same reason, doctors do not operate on members of their own family, and lawyers say that an attorney who represents himself in court has a fool for a client.
Political agendas are yet another kind of red flag. Government policies, and debates about those policies, depend on a wide range of specialized knowledge, from physics to medicine to economics to military strategy. Like the rest of us, experts in these fields can have political views that sometimes bias their judgment about the facts.
We should be careful, however, to weigh these factors fairly. A red flag is merely a warning sign; it raises a question but does not answer it.
An ad hominem argument rejects or dismisses another person’s statement by attacking the person rather than the statement itself.
Note that this is different than evaluating credibility.
If someone defends a position by citing an authority, as we have seen, then it is legitimate to consider evidence regarding the authority’s competence and objectivity. When a jury is asked to accept the testimony of a witness, it is certainly legitimate for the opposing side to introduce evidence that the witness is dishonest or biased.
Importantly, dicrediting witnesses says nothing about the truth/false of a statement.
But discrediting witnesses or authorities does not provide evidence that what they say is actually false; it merely eliminates any reason for thinking that what they say is true. So we go back to square one: We are left with no evidence one way or the other.
In personal disputes, disagreement often breeds anger, and angry people hit below the belt. In politics, ad hominem arguments are a common technique of propaganda and a common device of politicians who try to enlist support by attacking their enemies. But the fallacy can also take more sophisticated forms. Let’s look at a few.
Suppose that someone criticizes you for telling a white lie. If your critic is himself a notorious liar, you would probably be tempted to say, “Look who’s talking!” This response is certainly understandable—no one enjoys being censured by a moral inferior— but it is fallacious. … The fact that someone else is guilty of an accusation doesn’t prove that you are innocent.
The classic example is the patient who says to his doctor: “How can you tell me I should stop smoking when you still smoke yourself ?” The fact that a doctor doesn’t take his own advice hardly means that it isn’t good advice; a hypocrite may still say something true or make a valid argument.
In the constitutional struggles of the seventeenth century, the modern theory of natural law—the theory of individual rights—was eventually perfected. Stripped of the trappings which each particular theorist hung upon it, the bare theory was a simple pattern of … assumptions which, in the opinion of the men whose interests they served, were as obviously true as the axioms of Euclid. [Richard Schlatter, Private Property]
Here is AOR’s analysis.
The natural law theory in politics said that individuals had certain inalienable rightsthat government could not violate, including the right to acquire and dispose of private property. This passage describes one aspect of the theory: that such rights were held to be self-evident, like axioms of geometry. The author clearly does not agree with this view. But instead of presenting a reasoned argument against it, he takes a shortcut: He implies that the principle of property rights seemed self-evident only because it served the political interests of those who were wealthy. This tactic is sometimes called “poisoning the well,” and it is obviously fallacious. The fact that someone might have a nonrational motive for supporting a position does not mean the position is false, and it certainly does not mean we can decide ahead of time that all his arguments for the position can be dismissed.
Fallacies in this category include arguments that “jump to conclusions.” Although some of these fallacies can be cast in the form of deductive arguments, what makes them fallacious is a weak inductive component. … The problem is not the premises per se. Unlike the subjectivist fallacies, the premises of these arguments do provide genuine evidence. But the evidence is simply inadequate or incomplete in ways that the argument overlooks.
The essence of the fallacy, however, is not the number of alternatives but the fact that they do not exhaust the possibilities. That can occur whether an argument posits two, three, or any number of alternatives. If the list is incomplete—if it excludes a further alternative that is relevant to the issue—the argument is fallacious.
The Latin name of this fallacy is short for post hoc ergo propter hoc: “after this, therefore because of this.”
“Why are you whistling?”
“To keep the elephants away.”
“But there aren’t any elephants around here.”
“See? It works.”
Someone, somewhere, had a run of bad luck and attributed it to breaking a mirror, walking under a ladder, stepping on a crack, or some other previous action. A student does well on an exam and thereafter always wears the same “lucky” sweater on exam days. More serious examples of the fallacy occur in situations where causal relationships are extremely complex and difficult to identify. Stock market advisers, for instance, sometimes make predictions on the basis of a few indicators that happened to precede a previous rise or fall in prices. Post hoc reasoning can also occur in speculation about the causes of historical events such as the Civil War, the causes of economic phenomena such as the Great Depression, or the causes of sociological trends such as crime rates.
Some examples of generalization.
But we often draw conclusions too quickly, on the basis of insufficient evidence. This fallacy, known as hasty generalization, can take many forms.
A single bad experience while traveling can prejudice our view of an entire city or country (as in 3 above). Most of us have stereotypes about ethnic groups, professions, or people from different regions of the country, based on our exposure to a few individuals (as in 4 and 5 above). Even a judgment about the character or personality of an individual is a generalization drawn from our observation of that person on specific occasions; here, too, we often jump to conclusions. And we can jump to conclusions about ourselves: We make a mistake, fail a test, have a problem in a relationship, and then draw a sweeping conclusion about our inadequacies.
Two contextual factors are especially important if we want to avoid hasty generalization: the number and the variety of cases in the sample from which we generalize.
There is also a fallacy, called accident, that can occur when we move in the opposite direction by applying a generalization to a particular case.
The classic examples of accident involve the application of moral principles to particular situations. Take the principle that one should always tell the truth. What if a mugger on the street asks you where you live?
Another common form of accident is extrapolating a generalization beyond the range in which we established its truth. For example, we have all learned that water boils at 212ºF. But that measurement was made at sea level. It would be fallacious to assume that the generalization is true for all locations. That’s not the case, as you have probably also learned. At higher altitudes, where the atmospheric pressure is lower, water boils at lower temperatures.
This refers to arguing against a proposed action or policy by claiming, with insufficient evidence, that it will lead to a series of increasingly bad consequences. Some examples.
Another example about free speech.
We should oppose any effort by government to censor obscene books, movies, or other forms of expression, no matter how offensive we may find such material. The reason is that once government has the power to ban obscenity, that precedent will open the door to further controls on speech: banning racist remarks, then speech that the majority finds offensive, then speech that opposes government policies, and so on until no one is free to say anything without government permission.
Slippery slope arguments can be good ones if the slope is real—that is, if there is good evidence that the consequences of the initial action are highly likely to occur. The strength of the argument depends on two factors. The first is the strength of each link in the causal chain; the argument cannot be stronger than its weakest link. The second is the number of links; the more links there are, the more likely it is that other factors could alter the consequences.
The argument for free speech, for example, posits a series of steps by which government would expand its control over more and more kinds of speech, once the precedent of censoring pornography was established. The argument assumes that government seeks to expand its power over people. Even if that is true, however, it does not mean that government can expand its power indefinitely without provoking opposition. So we can’t assume that a ban on obscenity—the first step down the slope—will lead inexorably to censorship of all speech. Since each step is more intrusive than the one before, it is plausible that each step would provoke more opposition and thus become less likely. At best, therefore, this is a weak argument. Because it assumes that government power will expand inexorably, without recognizing any other factor, I would say that it is also fallacious.
Slippery slope arguments are very common in discussions of social and political issues. At the same time, such arguments are often used to persuade other people of a conclusion that the arguer has accepted for other, deeper reasons. … But putting forward a slippery slope argument when it is not the main reason one accepts a conclusion is rather disingenuous.
The fallacy of composition consists in inferring that what is true of a part must be true of the whole. The fallacy of division is the mirror image of composition: It is the inference that what is true of the whole must be true of the parts.
Another pair of examples.
government economic planning by asking, “Why is planning considered a good thing for individuals and business but a bad thing for the national economy?” The fact that individuals need to plan how they are going to earn a living and spend their income does not imply that society as a whole should plan how wealth should be produced and distributed throughout the economy. Whether national planning is a good idea depends on a host of other questions, such as whether government planners are capable of performing this task, and whether they have the right to supersede the decisions that individuals and businesses make about how to use their resources. Because the editorial ignores these issues and makes a simple inference to parts to the whole, the argument is a case of composition.
In the previous sections, we examined arguments that are fallacious either because they introduce irrelevant considerations into the reasoning process (emotions, threats, personal traits) or because they fail to consider a wide enough context of information. In this section, we’ll examine fallacies that involve more subtle logical errors within the argument itself.
Begging the question is the use of a proposition as a premise in an argument intended to support that same proposition.
For example: “[l] Society has an obligation to support the needy, because [2] people who cannot provide for themselves have a right to the resources of the community.”
Suppose I am arguing with an atheist about the existence of a supreme being. He asks why I believe that God exists, and I say, “Because the Bible says so.” If he then asks why he should take the Bible’s word for it, and I answer that the Bible is trustworthy because it is the Word of God, I am arguing in a circle: My premise assumes the existence of God, which was precisely the question at issue.
Suppose I accuse you of having cheated on a test, and when you deny it I say, “Why are you lying to me?” Any answer you give will imply that you were indeed lying, and thus that you did cheat.
The fallacy of equivocation occurs when a word switches meaning in the middle of the argument—when it expresses one concept in one premise and another concept in another premise or in the conclusion.
[Letter] grades are a crude and mechanical device that does not measure the nuances of student performance.
Student work should not be graded [evaluated].
This fallacy consists in the argument that a proposition is true because it hasn’t been proven false. … This is a fallacy because a lack of evidence for –p does not imply that there is evidence for p. All it means is that we do not know that –p is true.
I can’t prove that a storm is not brewing in the atmosphere of Jupiter, but that would hardly count as evidence that a storm is brewing.
In the preceding examples of the fallacy, the proposition p was a positive claim: that X is having an affair, that a storm is brewing on Jupiter. But the fallacy can also be committed when p is a negative claim. The absence of evidence that X is having an affair does not prove that he isn’t; the absence of evidence that a storm is brewing doesn’t prove that one isn’t.
As a rule, it is the positive claim that puts the ball in play and the positive claim that carries the initial burden of proof. If someone makes an unsupported statement, therefore, the proper response is not to make an equally unsupported denial. Nor should you accept the burden of disproving the person’s statement; if you do, you are cooperating in an implicit appeal to ignorance. (This is a trap that paranoid people often spring on their listeners: They make an arbitrary claim about a conspiracy against them and then take their claim to be vindicated unless others can disprove it.) The proper response is simply to point out that the claim is unsupported and ask the person to provide some evidence for it. If evidence is forthcoming, then the ball is in your court; if you do not find the evidence convincing, it is your responsibility to explain why.
One application of this rule is the legal principle that a person is innocent until proven guilty. To assert that someone is guilty is to make a positive claim: that the person committed a certain act. Thus in a court of law, the burden of proof rests with the party who brings the charges.
Here is a smaller diversion I thought of.
Mueller could not prove Trump did not obstruct justice, but that did not mean Trump obstructed justice.
Note that this is slightly different from Mueller did not conclude Trump did not obstruct. There are at least three possible scenarios: 1. Mueller couldnot make conclusions about this case. 2. Mueller could make conclusions. 2.a Mueller concluded Trump obstructed justice; 2.b Mueller concluded Trump did not. What Mueller said is essentially 1. Notably, democrats tried to push him to acknowledge 2.a. See here by Ted Lieu. Note that Mueller walked back from he “didn’t charge Trump because of the OLC opinion.” Note OLS stands for the Justice Department Office of Legal Counsel.
In the morning before the House Judiciary Committee.
Lieu: I’d like to ask you the reason, again, that you did not indict Donald Trump is because of OLC opinion stating that you cannot indict a sitting president, correct? Mueller: That is correct.
In the afternoon before the House Intelligence Committee.
Now, before we go to questions, I want to go back to one thing that was said this morning by Mr. Lieu who said, and I quote, “You didn’t charge the president because of the OLC opinion.” That is not the correct way to say it. As we say in the report, and as I said at the opening, we did not reach a determination as to whether the president committed a crime.
The fallacy of diversion consists in changing the issue in the middle of an argument. … Diversion works best when the nonrelevant conclusion arouses powerful emotions. For this reason, a nonrelevant issue is sometimes called a red herring—herring turns red when it is smoked, and a smoked fish has such a powerful smell that dragging it across the ground will throw a dog off the scent.
you go to the library one evening and miss a call from your mother. There may have been no way to anticipate the call. Even if there was, you may have felt that doing work at the library was more important and that missing the call would have to be an unfortunate by-product of going there. To prove that you were deliberately trying to avoid the call, we would need some positive evidence of that intent. It would be diversion to argue that you wanted to miss the call if the only evidence is that you did go to the library. In the same way, it would be fallacious to argue that the U.S. Labor Department is controlled by labor unions just because some decision turns out to be of benefit to union members; once again, we need evidence of intent, not merely of consequence.
suppose you are a student in my class, and you come to me with the suggestion that I allow more class discussion. I would commit the straw man fallacy if I replied: “I don’t want to give the entire class period over to an aimless bull session, because no one would learn anything.”
I will need to pick some in-class quizzes.
This section is mostly notes about the fallacy chapter from the Art of Reasoning by David Kelly..